im not worried about the "maybe" line from pa kent. first of all, those lines of dialogue may not be consecutive in the actual film. it may have just been edited that way to create a narrative for the trailer. trailers do that a lot.

secondly, if it is how the lines actually play out, the context of it could just be Jonathan helping clark see all the options available in order to make the right decision.

but i highly doubt Jonathan would ever actually entertain the idea to let people die if there was a way to stop it....unless the writers of the movie really just have a complete misunderstanding of the character.